This invention relates to battery testing techniques, and more specifically relates to automated apparatus and methods for testing and evaluating conventional lead storage batteries.
In the past, lead storage batteries have been tested by a variety of manual techniques which basically consist of charging the battery and then measuring the voltage after a predetermined load has been placed on the battery. Experience has shown that this technique results in defective batteries being passed and acceptable batteries being rejected Difficulties in separating defective from acceptable batteries have been encountered with warranty programs which typically extend over several months or years of use by a customer. Customers bring in batteries for warranty service in various states of charge and condition resulting from many different types of use. Prior testing techniques were incapable of separating good batteries from bad ones, and also were more expensive or lengthy than customers would tolerate. The tests also required too much discretion on the part of service personnel.
Basically, the applicants have discovered that a battery can be quickly and accurately analyzed by operating it in a charge-discharge cycle of operation, generating battery parameter values corresponding to the battery parameters at different points in time during the charge-discharge cycle of operation, storing the battery parameter values, calculating the condition of the battery based on the stored parameter values and displaying the calculated results. Preferably, the battery is discharged both before and after it is charged in order to provide battery parameter values under different conditions which enable accurate diagnosis of the battery.
As explained in detail in the specification, the applicants have discovered various combinations of battery parameters, such as voltage, current or temperature, by which the condition of a battery can be accurately determined. Each of these unique features can be understood from the following description of the preferred embodiment. By using the described techniques, batteries can be quickly and economically diagnosed with a degree of accuracy previously unattained.